Mammography: EUSOBI recommendations for women’s information

Mammography is the most important imaging procedure for breast cancer detection and diagnosis. It can be performed in a screening setting or a diagnostic setting.

The best time for mammography to be carried out is from day 7 to day 12 after the beginning of the woman’s last menstruation. This is due to cyclical variations in breast density. No particular scheduling is required after menopause. If the woman is pregnant, ultrasound is preferred as first option.

Note B. You should bring images and reports from the previous mammogram (and from other recent breast imaging examinations) and give these to the radiographer or to the radiologist before the procedure. This can be crucial for image interpretation, due to the fact that some cancers are diagnosed only on the basis of changes that have occurred since a previous exam.

Mammography is performed using a dedicated X-ray unit. A particular radiographic technique is used which requires the compression of the breast for 5–10 s in order to deliver a low radiation dose and to obtain high-quality images. It is standard practice to take two views per breast. Further additional views (projections) are acquired in special cases.

The procedure is performed with the woman’s upper body undressed. All foreign objects (such as bras, necklaces, piercings, etc.) must be removed before the procedure. The woman will stand in an upright position in front of the machine. For each projection of each breast, the radiographer will place the breasts on the plate and will apply a progressive compression for 5–10 s. During breast squeezing, women may feel some pain or discomfort [4]. It is important not to move during this short time. Immediately after acquiring the mammogram, the breast will be released from compression. The entire bilateral standard procedure, including preparation, takes approximately 5–10 min.

Note C. To reduce pain or discomfort due to compression and to get the best mammograms, you should relax during the procedure; in particular, pectoral muscles should be relaxed. Follow the radiographer’s instructions exactly, and bear in mind that heavier compression means a lower X-ray dose, higher image quality, and easier diagnosis. If you previously experienced a painful mammography in the premenstrual phase, try to arrange the next one from day 7 to day 12 of your cycle.

When the procedure is over, the woman returns to the waiting room. In the case of screening mammography, she is usually only informed whether or not the acquired images are technically adequate. If no views need to be repeated, she may leave. She will receive a letter communicating either that the mammogram is negative or that further assessment is needed (recall). The first event is far more probable (over 90–95% of cases). In the case of diagnostic mammography, after checking technical adequacy, the radiologist informs the patient either that the exam is completely negative or that further assessment is needed, which may include additional mammographic views, ultrasound, magnetic resonance imaging, and/or needle biopsy. In the diagnostic setting, the second event is more probable.

Note D. If you are recalled after a screening mammogram or you are asked to have an ultrasound after diagnostic mammography, this does not mean that you have cancer. The most probable result of this second examination is a higher level of certainty in stating that you do not have cancer! Less than 10% of women who are recalled at screening are finally diagnosed with cancer. However, if a cancer is present, you would rightly like it to be diagnosed as early as possible.

Diagnostic mammography and also diagnostic assessment of recalled women after mammography screening should be formally carried out by a certified breast radiologist. A detailed report should include a description of the clinical context, if relevant, as well as image findings, including breast density and structure according to different classification systems, interpretation and a final conclusion with recommendations.

In many European countries, standardised classification systems for the conclusions of mammography reports are used. A European system uses the five-level scale from R1 to R5 (where R stands for radiography). R1 means no abnormalities, R2 benign findings, R3 equivocal findings, R4 suspected cancer, R5 strongly suspected cancer. A system developed in the United States [Breast Imaging Reporting and Data System (BIRADS)] includes a similar scale from BI-RADS 1 to BI-RADS 5, with the same meaning for scores 1, 2, 4, and 5. The main difference is in BI-RADS 3, which means a very low probability of cancer (less than 2%), allowing the possibility of waiting for a short-interval (usually 3–6 months) before a repeat mammogram. The R3 category indicates a probability of cancer that is higher than BI-RADS 3. Moreover, the BI-RADS score system also includes BI-RADS 0 (examination insufficient for a diagnostic conclusion; further work-up needed) and BI-RADS 6 (evaluation of an already diagnosed cancer).

Note E. In practice, if you have an R4–R5 or BI-RADS 4–5 finding, needle biopsy is recommended. In case of R3 or BI-RADS 3, meet your radiologist and ask for a detailed explanation of this result, of the risks and of the probabilities associated with different options.

No diagnostic test is perfect. This rule also applies to mammography. When thinking about screening, women should be aware that about one-third of cancers can be missed, especially in pre-menopausal women and in those with dense breasts or those with a lot of breast tissue who also have a higher risk for breast cancer [5, 6].

Note F. Do not underestimate the importance of breast symptoms (especially a new palpable lump, skin/nipple retraction or nipple discharge), regardless of the timing of your last negative screening mammography. Go to your radiologist and ask for a visit. Tell her/him your symptoms and she/he will decide the best course of action for you.

Conversely, not all suspicious findings visualised on a mammogram are cancers: depending on the level of suspicion, cancer is confirmed in 3–95% of the cases. When the suspicion is confirmed after further assessment, image-guided needle biopsy is mandatory before planning the treatment.

Note G. A suspicious mammographic finding is not a confirmed cancer. However, do not postpone further assessment and, if necessary, needle biopsy.

The radiation exposure for a mammogram is very low. A recent study [7] reported that undergoing annual mammography from age 40 to 55 years and biannual mammography from 56 to 74 years entails a risk of radiation-induced breast cancer equal to 1 in every 1,000 women screened. The risk of breast cancer in the female population is equal to at least one in every ten women. The first risk is 100 times smaller than the second while the reduction in breast cancer mortality thanks to early detection with screening mammography is equal to 44–48% [8, 9]. In practice, the decision to undergo screening mammography halves the risk of death from breast cancer while increasing the risk of breast cancer by only 0.1%.

Not all the breast cancers diagnosed with screening are aggressive and fatal cancers. In the absence of screening mammography, some of them (probably 5–20%) would have remained totally free of symptoms [10]. However, these cancers cannot be distinguished from those that, if left undiagnosed and untreated, would be fatal. Thus, if we want to reduce breast cancer mortality, we must accept a rate of overdiagnosed cancers with the consequence of a rate of unnecessary treatments.